.\" $OpenBSD: mbsrtowcs.3,v 1.4 2012/06/07 19:47:40 matthew Exp $
.\" $NetBSD: mbsrtowcs.3,v 1.6 2003/09/08 17:54:31 wiz Exp $
.\"
.\" Copyright (c)2002 Citrus Project,
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.Dd $Mdocdate: June 7 2012 $
.Dt MBSRTOWCS 3
.Os
.\" ----------------------------------------------------------------------
.Sh NAME
.Nm mbsrtowcs ,
.Nm mbsnrtowcs
.Nd converts a multibyte character string to a wide-character string \
(restartable)
.\" ----------------------------------------------------------------------
.Sh SYNOPSIS
.Fd #include <wchar.h>
.Ft size_t
.Fn mbsrtowcs "wchar_t * restrict dst" "const char ** restrict src" "size_t len" \
"mbstate_t * restrict ps"
.Ft size_t
.Fn mbsnrtowcs "wchar_t * restrict dst" "const char ** restrict src" "size_t nmc" \
"size_t len" "mbstate_t * restrict ps"
.\" ----------------------------------------------------------------------
.Sh DESCRIPTION
The
.Fn mbsrtowcs
function converts the multibyte character string indirectly pointed to by
.Fa src
to the corresponding wide-character string and stores it in the
array pointed to by
.Fa dst .
The conversion stops due to the following reasons:
.Bl -bullet
.It
The conversion reaches a null byte.
In this case, the null byte is also converted.
.It
The conversion has already stored
.Fa len
wide characters.
.It
The conversion encounters an invalid character.
.El
.Pp
The
.Fn mbsnrtowcs
function is equivalent to
.Fn mbsrtowcs
except that it will additionally stop the conversion after processing
.Fa nmc
bytes.
.Pp
Each character is converted as if
.Xr mbrtowc 3
is continuously called.
.Pp
After conversion,
if
.Fa dst
is not a null pointer,
the pointer object pointed to by
.Fa src
is a null pointer (if the conversion is stopped due to reaching a null byte)
or the address just past the last byte processed.
.Pp
If
.Fa dst
is not a
null pointer and the conversion is stopped due to reaching a null byte,
the state object pointed to by
.Fa ps
is set to an initial state after the conversion has taken place.
.Pp
The behaviour of the
.Fn mbsrtowcs
and
.Fn mbsnrtowcs
functions is affected by the
.Dv LC_CTYPE
category of the current locale.
.Pp
There are two special cases:
.Bl -tag -width 012345678901
.It "dst == NULL"
The conversion takes place, but the resultant wide-character string
is discarded.
In this case, the pointer object pointed to by
.Fa src
is not modified and
.Fa len
is ignored.
.It "ps == NULL"
The
.Fn mbsrtowcs
and
.Fn mbsnrtowcs
functions use their own internal state objects to keep the conversion state,
instead of
.Fa ps
as mentioned in this manual page.
.Pp
Calling any other functions in
.Em libc
never change these internal states,
which are initialized at startup time of the program.
.El
.\" ----------------------------------------------------------------------
.Sh RETURN VALUES
The
.Fn mbsrtowcs
and
.Fn mbsnrtowcs
functions return:
.Bl -tag -width 012345678901
.It 0 or positive
The value returned is the number of elements stored in the array pointed to by
.Fa dst ,
except for a terminating null wide character (if any).
If
.Fa dst
is not null and the value returned is equal to
.Fa len ,
the wide-character string pointed to by
.Fa dst
is not null terminated.
If
.Fa dst
is a null pointer, the value returned is the number of elements to contain
the whole string converted, except for a terminating null wide character.
.It (size_t)-1
The array indirectly pointed to by
.Fa src
contains a byte sequence forming invalid character.
In this case,
.Va errno
is set to indicate the error.
.El
.\" ----------------------------------------------------------------------
.Sh ERRORS
The
.Fn mbsrtowcs
and
.Fn mbsnrtowcs
functions may return the following errors:
.Bl -tag -width Er
.It Bq Er EILSEQ
The pointer pointed to by
.Fa src
points to an invalid or incomplete multibyte character.
.It Bq Er EINVAL
.Fa ps
points to an invalid or uninitialized mbstate_t object.
.El
.\" ----------------------------------------------------------------------
.Sh SEE ALSO
.Xr mbrtowc 3 ,
.Xr mbstowcs 3 ,
.Xr setlocale 3
.\" ----------------------------------------------------------------------
.Sh STANDARDS
The
.Fn mbsrtowcs
function conforms to
.\" .St -isoC-amd1 .
ISO/IEC 9899/AMD1:1995
.Pq Dq ISO C90, Amendment 1 .
The restrict qualifier is added at
.\" .St -isoC99 .
ISO/IEC 9899/1999
.Dq Pq ISO C99 .
.Pp
The
.Fn mbsnrtowcs
function conforms to
.St -p1003.1-2008 .